diff --git a/Makefile b/Makefile
index e721092..846874e 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-CFLAGS=-Wall -Wextra -pedantic-errors -g -DNDEBUG
+CFLAGS=-Wall -Wextra -pedantic -g -DNDEBUG
 
 EXERCISES = $(patsubst %.c,%,$(shell ls ex*.c | egrep -v "ex(19|22)"))
 
diff --git a/ex15.c b/ex15.c
index 1621a1c..8480c5d 100644
--- a/ex15.c
+++ b/ex15.c
@@ -81,7 +81,7 @@ int main(int argc, char *argv[])
     int i;
     char **arg = argv;
     for(i = 0; i < argc; i++) {
-        printf("argument %d is '%s' (address = %p)\n", i, *arg, arg);
+        printf("argument %d is '%s' (address = %p)\n", i, *arg, (void *)arg);
         arg++;
     }
 
diff --git a/ex16.c b/ex16.c
index e586bab..9b4c240 100644
--- a/ex16.c
+++ b/ex16.c
@@ -15,7 +15,7 @@ struct Person *Person_create(char *name, int age, int height, int weight)
     struct Person *who = malloc(sizeof(struct Person));
     assert(who != NULL);
 
-    who->name = strdup(name);
+    who->name = strdup((char *)name);
     who->age = age;
     who->height = height;
     who->weight = weight;
@@ -49,10 +49,10 @@ int main(int argc, char *argv[])
             "Frank Blank", 20, 72, 180);
 
     // print them out and where they are in memory
-    printf("Joe is at memory location %p:\n", joe);
+    printf("Joe is at memory location %p:\n", (void *)joe);
     Person_print(joe);
 
-    printf("Frank is at memory location %p:\n", frank);
+    printf("Frank is at memory location %p:\n", (void *)frank);
     Person_print(frank);
 
     // make everyone age 20 years and print them again
diff --git a/ex18.c b/ex18.c
index 5a5a77a..f6735b3 100644
--- a/ex18.c
+++ b/ex18.c
@@ -81,7 +81,7 @@ void test_sorting(int *numbers, int count, compare_cb cmp)
 
     free(sorted);
 
-    unsigned char *data = (unsigned char *)cmp;
+    unsigned char *data = (unsigned char *)&cmp;
 
     for(i = 0; i < 25; i++) {
         printf("%0x:", data[i]);